Electronic systems and circuits have made a significant contribution towards the advancement of modern society and are utilized in a number of applications to achieve advantageous results. Numerous electronic technologies such as digital computers, calculators, audio devices, video equipment, and telephone systems facilitate increased productivity and cost reduction in analyzing and communicating data, ideas and trends in most areas of business, science, education and entertainment. Frequently, these activities involve significant information processing. However, the speed at which a processor can reliably provide accurate results is limited and typically degrades over time. Most systems limit processor operation within conservative boundaries and sacrifice possible increased performance so that the processor can meet reliability standards.
Advanced applications are creating ever greater demands for faster processor performance. For example, the desired objective of numerous applications is to provide a visual presentation to a user (e.g., on a display monitor). Displaying information in a visual presentation is usually a convenient and effective method of conveying the information. Display devices (cathode ray tube monitors, liquid crystal displays, etc.) usually present images by coordinating the illumination characteristics of numerous picture elements (pixels). However, many graphics presentations, especially interactive 3D graphics presentations, usually require significant processing of large amounts of data at a rapid rate. Providing image information for each pixel is very data intensive and consumes a significant amount of processing resources. Advanced graphics applications such as three dimensional graphics utilized in modern gaming applications require significant amounts of information associated with each pixel (e.g., primary color intensity, transparency, brightness, texture and shading) to be produced at rates fast enough to provide a smooth and interactive presentation.
Graphics information generation is often best performed by dedicated graphics subsystem resources including graphics processor units. Separate graphics processors relieve the central processor of performing many of the graphics processing tasks. Graphics processors are usually specifically configured for performance of graphics activities enabling a graphics processor to perform many graphics operations faster and more efficiently than a central processor.
The amount of information and speed at which it is processed by a processor is determined by a variety of factors. For example, the number of transistors and their configuration on the chip usually affect the bandwidth and speed at which the processing can occur. Generally, a larger number of transistors can process information quicker than a smaller number of transistors operating at the same clock frequency. However, at some point increasing the number of transistors becomes cost prohibitive. Another factor that affects the processing speed is the clock frequency. A processor typically performs operations in a sequence of events (e.g., fetching, decoding and executing instructions), the order and timing of which are usually critical. A processor typically relies upon a clock signal to provide appropriate synchronization and satisfy requisite timing constraints. However, increasing the clock frequency is often limited by the characteristics of the transistors utilized to perform the processing. Higher voltages can be used to sustain operations at a higher clock frequency, and higher clock frequencies and voltage supplies cause a processor to consume more power, thereby increasing the temperature of the processor. However, higher temperatures generally cause transistors to operate more slowly, causing a lower operational transistor speed. Continually running a processor at a high temperature stresses the semiconductor device and reduces long term reliability of the device.
The basic electronic component for performing most of the switching operations in a processor is a transistor. There are a number of factors that can affect the degradation of a transistor's ability to quickly and reliably perform switching operations. For example, the drain current saturation (Id,sat) is one of the underlying physical mechanisms involved in transistor switching operations and is often utilized to indicate how fast a transistor can perform switching operations. The drain current saturation rating of a transistor can be adversely impacted by the temperature and voltage level at which the transistor is operating, causing deterioration in the transistor switching speed. These limitations impact maximum clock frequencies since transistor reliability is often degraded over time by increased voltage levels and temperatures associated with relatively high clock frequencies.
Most processors are identified by a particular fixed nominal clock frequency at which the processor is expected to provide reliable results over a specific life span (e.g., 10 years). Numerous systems operate the processor at the fixed nominal clock frequency continuously for the life of the processor even though a task does not require the level of processing speed provided by the fixed nominal clock frequency. The fixed nominal frequency is typically not the fastest frequency the processor can possibly operate at and resource utilization is not maximized. To the extent traditional processing systems attempt clock frequency adjustment, they are usually limited to downward adjustments from the fixed nominal clock frequency to achieve power conservation, further limiting the maximization of processor performance speed. Some traditional processing systems also attempt to make various adjustments in response to temperature measurements. These attempts are also typically limited in scope (such as a single specific adjustment) and usually have limited or no consideration for impacts on processing performance (e.g., maximized processing speed) or environment (e.g., noise level). Traditional attempts at processor control typically have limited or no consideration for impacts of frequency, voltage and/or temperature adjustments on maximizing performance while maintaining overall lifetime reliability.